The origins of DNA were first discovered in 1857 by Gregor Mendel, the "father of genetics", who was performing a genetics experiment with pea plants and would provide a basis basis for DNA and genetics Friedrich Miescher and Richard Altmann in 1869 were also among the first to discover DNA. While testing the sperm of a salmon, they discovered a strange substance that they called "nuclein", which is known as DNA Yes discovered that "nuclein" (DNA) exists only in chromosomes. Frederick Griffith, a researcher, found the basis on DNA, from an experiment on the inheritance of the molecule involving mice and two types of pneumonia. His findings were that when the virulent disease is heated (to kill) and injected into a mouse, the mouse survives unlike the second mouse that was injected with a non-virulent disease and the virulent disease (which had been heated and killed) is killed inheritance of molecules (transformation) of virulent bacteria that transmit a characteristic to non-virulent bacteria. DNA results will continue to be tested and we will seek to better understand how DNA works. Deoxyribonucleic acid (DNA) is a chromosome found in the nucleus of a cell, which is a double-stranded helix (similar to a twisted ladder). DNA is made up of four bases called adenine (A), thymine (T), guanine (G) and cytosine (C), which is always based on pairs of A with T and G with C. The four bases of A, C , G and T were discovered by Phoebus Levene in 1929, who linked them to the string of nucleotide units through phosphate-sugar base (groups). As mentioned in Ananya Mandal's research paper, Levene thought that the chain connection with the bases repeats in a fixed order that constitutes the DNA molecule... in the center of the sheet... stody." TheFreeDictionary.com. Np , n.d. Web. 10 December 2013. Wikipedia Contributors, . Np Web 10 December 2013. .Norrgard, “Forensics, DNA Fingerprinting and CODIS Nature Publishing Group.” Wittmeyer, Jacqui. West Virginia, n.d. Web. December 10, 2013. “Learn: DNA Profiling” Unit 3 Evidence Traces, Lesson 7 from SCI030: Forensic Science Course